Sinkholes are one of the most hazardous phenomena due to their occurrence and
unpredictability. In the Friuli Venezia Giulia Region (northeast Italy), the presence of
outcropping, mantled or capped evaporites is the main predisposing factor for these
phenomena. Even if evaporites do not exceed 1% of the entire regional territory, their
presence causes catastrophic events mainly in the Carnian alpine valleys. Chalks are
included in the Bellerophon Formation (Late Permian) and in the Raibl one (Upper Carnian).
These weak rocks are mainly located in the valley bottoms and not at the top of the
mountains. Even if, in correspondence of the northern ridges of Sauris municipality, several
sinkholes have been observed. In detail, north of Sauris, quartz sandstones and mica-
siltstones belonging to the Werfen Formation (Triassic) are widely present. These rocks,
capping evaporitic ones, belonging to the Bellerophon Formation, are jointed and
characterized by a secondary permeability. Over time, water infiltration and weathering led to
the solution of the Permian evaporites and to
the progressive failure of the overlying
terrigenous rocks, less soluble but more plastic. The result is the genesis and evolution of
depressed landforms classifiable as sinkhol
es. On the grassy meadows stretching from
Sauris di Sopra to Sella Festons at 1800 m a.s.l., outstanding sinkholes can be observed at
the top as well as on the slope. Since now, almost 80 sinkhole phenomena were recognized
and classified in the Sauris Municipality; mo
st of them are aligned along approximately E-W
oriented faults. All the data were added and stored in a GIS, which represents the first
sinkhole inventory related to the evaporite karst environment in Friuli Venezia Giulia Region.
